In the Linux kernel, the following vulnerability has been resolved:
KVM: x86/mmu: Check write tracking in all address spaces
kvm_gfn_is_write_tracked() checks only the supplied memslot, but page
tracking is per-address-space and shadow pages are shared across all
address spaces. With SMM, a GFN can therefore be write-tracked in one
address space and appear untracked through the other.
Check the supplied slot first, then the slot for the other address space.
This ensures all callers honor write tracking regardless of the active
address space. In particular, it prevents mmu_try_to_unsync_pages() from
marking an upper-level shadow page unsync and eventually triggering the
BUG in pte_list_remove().
[invert direction of the conditional. - Paolo]
In the Linux kernel, the following vulnerability has been resolved:
cgroup: Avoid iteration of dying tasks with zero refcount
The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from
cgroup_task_release() to cgroup_task_free()") extended the lifetime of
tasks on the dying_tasks list.
The iterators have provision to go through dying_tasks because of
dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however,
it was expected that such tasks can obtain a new reference (that is
possible before cgroup_task_release()/put_task_struct_rcu_user()).
The tasks after cgroup_task_release() and before cgroup_task_free()
are subject to race when they may or may not have ->usage count > 0.
The race window is between css_task_iter_next() invocations
when css_set_lock is released and we may arrive at a new ->task_pos.
The iterator should not attempt to resurrect tasks whose ->usage count
dropped to zero. (When that happens, __put_task_struct_rcu_cb() is
already imminent and the returned task_struct would could be used
after free.)
As for the fix, we cannot simply check the signal->live count of a task
on the dying list because that won't distinguish regular zombies waiting
to be reaped from RCU remnant tasks that are going to be free'd.
Therefore add an extra check to rule out ->usage==0 tasks from any
iteration.
The repeat: loop in css_task_iter_advance() doesn't consider ->usage
count, so add a new loop to css_task_iter_next() to skip de-used tasks
on the dying_list.
Rough illustration of the possible race
R (reader of cgroup.procs) T (thread) L (group leader)
--------------------------------- -------------------------------- --------------------------------
L exits, signal->live > 0
cgroup_task_dead(L)
css_set_skip_task_iters() // skips only cset->tasks
list_add_tail(&L->cg_list, &cset->dying_tasks)
css_task_iter_next()
take css_set_lock
css_task_iter_advance()
leader && signal->live != 0
=> it->task_pos = &L->cg_list
release css_set_lock
T exits
--signal->live == 0
cgroup_task_dead(T) // css_set_lock
release_task(T)
cgroup_task_release(T)
release_task(L) // zap_leader
cgroup_task_release(L)
put_task_struct_rcu_user(L)
...RCU...
put_task_struct(L)
L->usage = 0
/* L still on dying_tasks */
...RCU...
__put_task_struct(L)
css_task_iter_next() // another iteration
take css_set_lock
it->task_pos = &L->cg_list
get_task_struct(L)
=> addition on 0
drop css_set_lock
cgroup_task_free(L)
css_set_skip_task_iters() // dying skip comes too late
free_task(L)
cgroup_procs_show()
task_pid_vnr(L)
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix mismatched free of HalData in rtw_sdio_if1_init()
padapter->HalData is allocated via vzalloc(), but incorrectly freed
using kfree() in the rtw_sdio_if1_init() error path. Using kfree() to
release this vmalloc-backed buffer can lead to memory corruption.
Use rtw_hal_data_deinit() to pair the free correctly and free
HalData with vfree().
The bug was first flagged by an experimental static analysis tool we
are developing for kernel memory-management bugs. Manual inspection
confirms that the issue is still present in current mainline.
An x86_64 allyesconfig build showed no new warnings. As we do not have
suitable RTL8723BS SDIO hardware to test with, no runtime testing was
able to be performed.
In the Linux kernel, the following vulnerability has been resolved:
nvdimm: pmem: keep PREFLUSH before data writes
pmem_submit_bio() records a REQ_PREFLUSH error, but continues to copy the
bio data and can later overwrite the error with a successful REQ_FUA flush.
That lets data writes run after a failed preflush and can complete the bio
successfully despite the failed ordering barrier.
Run the REQ_PREFLUSH flush synchronously before touching the bio data and
complete the bio with the flush error if it fails. Keep asynchronous flush
chaining for REQ_FUA. At that point, data copy has completed and the parent
bio can wait for the chained flush bio.
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: ucsi: unregister debugfs entries on teardown
ucsi_register() creates per-instance debugfs entries, but
ucsi_unregister() keeps them around until ucsi_destroy().
Drivers like ucsi_glink that unregister/register the same UCSI
instance across remoteproc restart then try to create an already
existing debugfs directory and log:
debugfs: 'pmic_glink.ucsi.0' already exists in 'ucsi'
Unregister debugfs entries as part of ucsi_unregister(), and
clear ucsi->debugfs after freeing it so repeated unregister
paths remain safe.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters
When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect
descriptor, the unwind path destroys RDMA contexts but leaves stale
n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later
sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending()
can then subtract the wrong number of send queue credits.
Reset the counters and clear rw_ctxs after freeing the heap
allocation before returning an error.
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix xmit_frame/xmit_buf leaks on mgnt-frame error paths
issue_beacon(), issue_probersp() and issue_asocrsp() obtain a management
xmit_frame together with its xmit_buf from the driver's fixed-size
management-TX pools via alloc_mgtxmitframe(). On the normal path the frame
is handed to dump_mgntframe(), which transfers ownership and eventually
returns both objects to their pools (the frame and, for beacons, the buf
in rtl8723bs_mgnt_xmit(); other bufs via the pending-xmitbuf/TX-completion
path).
Several error/edge paths return early after a successful
alloc_mgtxmitframe() but before dump_mgntframe(), so ownership is never
transferred and neither object is freed:
- issue_beacon(): beacon larger than 512 bytes
- issue_probersp(): cur_network->ie_length > MAX_IE_SZ
- issue_probersp(): kzalloc() of the SSID scratch buffer fails
- issue_asocrsp(): pkt_type is neither ASSOCRSP nor REASSOCRSP
Because alloc_mgtxmitframe() removes the frame and buf from their free
lists (list_del_init) without placing them on any pending list, an
orphaned pair is on no list and referenced by nobody, so it is only
reclaimed at driver teardown. Repeated hits progressively exhaust the
management-TX pools until alloc_mgtxmitframe() returns NULL and the
interface can no longer send beacons or probe/assoc responses.
Free the frame and buffer on these paths, matching the existing correct
error handling in issue_assocreq().
In the Linux kernel, the following vulnerability has been resolved:
drm/msm: Recover HW before retire hung submit
During recovery, it is not safe to retire the hung submit before we
recover the GPU. Retiring the submit triggers BO free and that can
result in GPU pagefaults since the GPU may be actively accessing those
BOs.
To fix this, retire the submits after gpu recovery is complete in
recover_worker().
Patchwork: https://patchwork.freedesktop.org/patch/730655/
In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: mei: pass correct argument to function
The first argument to iwl_mei_write_cyclic_buf() should be the cldev
but the q_head pointer is passed instead. Fix it.
In the Linux kernel, the following vulnerability has been resolved:
bpf: Mark bpf_refcount field as unique
BPF_REFCOUNT is not marked as a unique field, while it should be. Fix
this oversight.